Study On Catalytic Fast Co-pyrolysis Of Biomass And Waste Plastic: On Py-GC/MS

Biomass is the only source of organic carbon in renewable energy sources,which can be converted to fuels and chemicals such as the alkenes, alkanes and aromatic hydrocarbons through catalytic pyrolysis technology. However, the catalytic pyrolysis bio-oil has relatively high oxy-organics and lower hydrocarbons due to the low effective hydrogen to carbon ratio of biomass. To solve the problem, the paper shows the experiments of biomass mixed with waste plastic by co-pyrolysis and with catalysts, and the liquid products were analyzed with Py-GC/MS.In this study, the fast pyrolysis experiments of sawdust and LDPE were carried on at the range of 450-650℃, the results showed that the selectivity of hydrocarbon compounds from fast pyrolysis of sawdust at 550℃ was higher and the oxygenate compounds furans, carbonyl complexes and so on were lower than those at other reaction temperature. For the fast pyrolysis of LDPE, the relative content of the small molecules hydrocarbon was markedly improved, and at 700 ℃ the content of hydrocarbon compounds（C5-C11） was the up to 71.9%. While one of the big molecules was decreased with increasing pyrolysis temperature. The co-pyrolysis experiments of sawdust and waste plastic with different mass ratio, the results show that promoted sawdust pyrolysis in different extent by adding LDPE with different mass. Catalytic fast pyrolysis of sawdust, LDPE, and their mixture with HZSM-5 and Na₂CO₃/γ-Al₂O₃, and catalytic co-pyrolysis experiments were investigated with different temperature, H/Ceff, and they had the improtant impact on the liquid products. The catalytic co-pyrolysis results showed that（1） HZSM-5 shows the strong abilities in decarboxylation, decarbonylation and selectivity of aromatics. Catalytic co-pyrolysis at 600 ℃, the selectivity of hydrocarbons compounds is increasing with H/Ceff increasing constantly, when H/Ceff=0.99,（C5-C11） reached its maximum 74.0% and（C12-C20） reached the minimum. At 650℃, the selectivity of hydrocarbons compounds is 89.4%, among them aromatics such as benzene, toluene, xylene, ethyl benzene was up to 17.0%.（2）Na₂CO₃/γ-Al₂O₃ shows the strong abilities in decarboxylation, splitting bond, and the selectivity of olefins. The distribution and selectivity of liquid products was improved continually, with the increasing of reaction temperature. The content of 91.6% of hydrocarbon compounds can be obtained at 650℃, where olefin was 70.3%, alkane was 14.0%, aromatics was 7.3%. Compared with the co-pyrolysis results of sawdust and waste plastic, the selectivity of hydrocarbons compounds in catalytic co-pyrolysis is increased to 14.9%.Catalytic co-pyrolysis of sawdust and waste plastic with HZSM-5 and Na₂CO₃/γ-Al₂O₃, the experiments show that the different role in composition distribution and selectivity of the liquid products. The HZSM-5 with strong acidity plays a strong selectivity of aromatics, while the Na₂CO₃/γ-Al₂O₃ with a break acidity has a strong selectivity of olefins.